"Initiative 29 prohibits retailers from selling or permitting the sale of a smartphone to a person under the age of 13, or to any person who indicates that the smartphone will be wholly or partially owned by a person under the age of 13," the proposal states.

"Retailers must verbally inquire about the age of the intended primary owner of the smartphone prior to the sale, document the response, and file a monthly report to the Department of Revenue."

Retailers who sell a smartphone for use by a preteen would get a warning for the first offense but could be fined from $500 to $20,000 for subsequent violations.

The founder of the group, Dr. Timothy Farnum, a board certified anesthesiologist, said earlier this month that once children get a smartphone, they change.

“They go from being outgoing, energetic, interested in the world and happy, to reclusive. They want to spend all their time in their room. They lose interest in outside activities." Farnum said.

“Eventually kids are going to get phones and join the world, and I think we all know that, but little children, there’s just no good that comes from that,” The Coloradoan quoted Farnum as saying.

Farnum said a toddler could experience speech and language difficulties after constantly looking at screens.

For children younger than 18 months, avoid use of screen media other than video chatting.

Parents of children 18 to 24 months of age who want to introduce digital media should choose high-quality programming, and watch it with their children to help them understand what they're seeing.

For children ages 2 to 5 years, limit screen use to one hour per day of high-quality programs. Parents should co-view media with children to help them understand what they are seeing and apply it to the world around them.

For children ages 6 and older, place consistent limits on the time spent using media, and the types of media, and make sure media does not take the place of adequate sleep, physical activity and other behaviors essential to health.

Designate media-free times together, such as dinner or driving, as well as media-free locations at home, such as bedrooms.

Have ongoing communication about online citizenship and safety, including treating others with respect online and offline.